Method and apparatus for receiving system information in the wireless communication

ABSTRACT

The present invention discloses a method for a user equipment to receive system information in a wireless communication system. Particularly, the method is characterized in detecting a first synchronization signal block configured with a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS) and a Physical Broadcasting Channel (PBCH) at a specific frequency position, determining a presence or non-presence of system information corresponding to the first synchronization signal block within a first synchronization raster corresponding to a specific frequency position based on a system information indicator included in the PBCH, and if the system information corresponding to the first synchronization signal block is determined as not existing, determining a second synchronization raster having system information exist therein based on the system information indicator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This applications a National Stage application under 35 U.S.C. § 371 ofInternational Application No. PCT/KR2018/006279, filed Jun. 1, 2018,which claims the benefit of U.S. Application No. 62/637,320, filed onMar. 1, 2018, U.S. Application No. 62/635,573, filed Feb. 27, 2018, U.S.Application No. 62/630,203, filed Feb. 13, 2018, and U.S. ApplicationNo. 62/514,922, filed Jun. 4, 2017. The disclosures of the priorapplications are incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a method of receiving systeminformation and apparatus therefor, and more particularly, to a methodof system information does not exist in a synchronization raster fromwhich a synchronization signal bloc is detected, obtaining informationon a system information existing synchronization raster and thenreceiving the system information and apparatus therefor.

BACKGROUND ART

As more and more communication devices demand greater communicationtraffic as times go by, the next generation 5G system, which is wirelessbroadband communication, is being required over the existing LTEsystems. In the next generation 5G system named NewRAT, communicationscenarios are classified into Enhanced Mobile BroadBand (eMBB),Ultra-reliability and low-latency communication (URLLC), MassiveMachine-Type Communications (mMTC), etc.

Here, eMBB is the next generation mobile communication scenario havingsuch properties as High Spectrum Efficiency, High User Experienced DataRate, High Peak Data Rate and the like, URLLC is the next generationmobile communication scenario having such properties as Ultra Reliable,Ultra Low Latency, Ultra High Availability and the like (e.g., V2X,Emergency Service, Remote Control), and mMTC is the next generationmobile communication scenario having such properties as Low Cost, LowEnergy, Short Packet, Massive Connectivity and the like (e.g., IoT).

DISCLOSURE OF THE INVENTION Technical Task

One technical task of the present invention is to provide a method ofreceiving system information and apparatus therefor.

Technical tasks obtainable from the present invention are non-limited bythe above-mentioned technical task. And, other unmentioned technicaltasks can be clearly understood from the following description by thosehaving ordinary skill in the technical field to which the presentinvention pertains.

Technical Solutions

In one technical aspect of the present invention, provided herein is amethod of receiving system information by a user equipment in a wirelesscommunication system, the method including detecting a firstsynchronization signal block configured with a Primary SynchronizationSignal (PSS), a Secondary Synchronization Signal (SSS) and a PhysicalBroadcasting Channel (PBCH) at a specific frequency position,determining a presence or non-presence of system informationcorresponding to the first synchronization signal block within a firstsynchronization raster corresponding to a specific frequency positionbased on a system information indicator included in the PBCH, and if thesystem information corresponding to the first synchronization signalblock is determined as not existing, determining a secondsynchronization raster having system information exist therein based onthe system information indicator.

Here, the second synchronization raster may be determined based on thefirst synchronization raster and a relative position of a valuecorresponding to the system information indicator.

A position of the second synchronization raster may have a spacingamounting to an offset value corresponding to the system informationindicator from a position of the first synchronization raster.

If the system information indicator indicates a specific value, thesystem information corresponding to the first synchronization signalblock may be determined as not existing within a predetermined frequencyrange.

If the system information indicator indicates the specific value, aposition of the second synchronization raster may not be determined.

And, the method may further include receiving a third synchronizationsignal block not having the system information at a frequency positionnot included in the first and second synchronization rasters.

In another technical aspect of the present invention, provided herein isa user equipment in receiving system information in a wirelesscommunication system, the user equipment including an RF moduletransceiving a wireless signal with a base station and a processorconfigured to control the RF module, wherein the processor is furtherconfigured to detect a first synchronization signal block configuredwith a Primary Synchronization Signal (PSS), a Secondary SynchronizationSignal (SSS) and a Physical Broadcasting Channel (PBCH) at a specificfrequency position, determine a presence or non-presence of systeminformation corresponding to the first synchronization signal blockwithin a first synchronization raster corresponding to a specificfrequency position based on a system information indicator included inthe PBCH, and if the system information corresponding to the firstsynchronization signal block is determined as not existing, determine asecond synchronization raster having system information exist thereinbased on the system information indicator.

Here, the second synchronization raster may be determined based on thefirst synchronization raster and a relative position of a valuecorresponding to the system information indicator.

A position of the second synchronization raster may have a spacingamounting to an offset value corresponding to the system informationindicator from a position of the first synchronization raster.

If the system information indicator indicates a specific value, thesystem information corresponding to the first synchronization signalblock may be determined as not existing within a predetermined frequencyrange.

If the system information indicator indicates the specific value, aposition of the second synchronization raster may not be determined.

And, the user equipment may further include receiving a thirdsynchronization signal block not having the system information at afrequency position not included in the first and second synchronizationrasters.

Advantageous Effects

According to the present invention, since a base station needs not totransmit system information on all bands on which a synchronizationsignal block is transmitted, an overhead can be reduced. Since a UserEquipment (UE) can scan a system information existing band quickly, itis able to effectively obtain system information necessary forcommunication with a network.

It will be appreciated by persons skilled in the art that that theeffects that could be achieved with the present invention are notlimited to what has been particularly described hereinabove and otheradvantages of the present invention will be more clearly understood fromthe following detailed description taken in conjunction with theaccompanying drawings.

DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram for structures of control and user planes of radiointerface protocol between a 3GPP radio access network standard-baseduser equipment and E-UTRAN;

FIG. 2 is a diagram for explaining physical channels used for 3GPPsystem and a general signal transmission method using the physicalchannels;

FIG. 3 is a diagram for a structure of a radio frame in LTE system;

FIG. 4 is a diagram illustrating a radio frame structure fortransmitting an SS (synchronization signal) in LTE system;

FIG. 5 illustrates a structure of a downlink radio frame in the LTEsystem;

FIG. 6 illustrates a structure of an uplink subframe in the LTE system;

FIG. 7 illustrates examples of a connection scheme between TXRUs andantenna elements.

FIG. 8 illustrates an example of a self-contained subframe structure;

FIG. 9 is a diagram to describe a UE accessible band and a UEnon-accessible band.

FIG. 10 is a block diagram of a communication apparatus according to anembodiment of the present disclosure.

BEST MODE FOR INVENTION

The configuration, operation, and other features of the presentdisclosure will readily be understood with embodiments of the presentdisclosure described with reference to the attached drawings.Embodiments of the present disclosure as set forth herein are examplesin which the technical features of the present disclosure are applied toa 3rd Generation Partnership Project (3GPP) system.

While embodiments of the present disclosure are described in the contextof Long Term Evolution (LTE) and LTE-Advanced (LTE-A) systems, they arepurely exemplary. Therefore, the embodiments of the present disclosureare applicable to any other communication system as long as the abovedefinitions are valid for the communication system.

The term ‘Base Station (BS)’ may be used to cover the meanings of termsincluding Remote Radio Head (RRH), evolved Node B (eNB or eNode B),Reception Point (RP), relay, etc.

FIG. 1 illustrates control-plane and user-plane protocol stacks in aradio interface protocol architecture conforming to a 3GPP wirelessaccess network standard between a User Equipment (UE) and an EvolvedUMTS Terrestrial Radio Access Network (E-UTRAN). The control plane is apath in which the UE and the E-UTRAN transmit control messages to managecalls, and the user plane is a path in which data generated from anapplication layer, for example, voice data or Internet packet data istransmitted.

A PHYsical (PHY) layer at Layer 1 (L1) provides information transferservice to its higher layer, a Medium Access Control (MAC) layer. ThePHY layer is connected to the MAC layer via transport channels. Thetransport channels deliver data between the MAC layer and the PHY layer.Data is transmitted on physical channels between the PHY layers of atransmitter and a receiver. The physical channels use time and frequencyas radio resources. Specifically, the physical channels are modulated inOrthogonal Frequency Division Multiple Access (OFDMA) for Downlink (DL)and in Single Carrier Frequency Division Multiple Access (SC-FDMA) forUplink (UL).

The MAC layer at Layer 2 (L2) provides service to its higher layer, aRadio Link

Control (RLC) layer via logical channels. The RLC layer at L2 supportsreliable data transmission. RLC functionality may be implemented in afunction block of the MAC layer. A Packet Data Convergence Protocol(PDCP) layer at L2 performs header compression to reduce the amount ofunnecessary control information and thus efficiently transmit InternetProtocol (IP) packets such as IP version 4 (IPv4) or IP version 6 (IPv6)packets via an air interface having a narrow bandwidth.

A Radio Resource Control (RRC) layer at the lowest part of Layer 3 (orL3) is defined only on the control plane. The RRC layer controls logicalchannels, transport channels, and physical channels in relation toconfiguration, reconfiguration, and release of radio bearers. A radiobearer refers to a service provided at L2, for data transmission betweenthe UE and the E-UTRAN. For this purpose, the RRC layers of the UE andthe E-UTRAN exchange RRC messages with each other. If an RRC connectionis established between the UE and the E-UTRAN, the UE is in RRCConnected mode and otherwise, the UE is in RRC Idle mode. A Non-AccessStratum (NAS) layer above the RRC layer performs functions includingsession management and mobility management.

DL transport channels used to deliver data from the E-UTRAN to UEsinclude a Broadcast Channel (BCH) carrying system information, a PagingChannel (PCH) carrying a paging message, and a Shared Channel (SCH)carrying user traffic or a control message. DL multicast traffic orcontrol messages or DL broadcast traffic or control messages may betransmitted on a DL SCH or a separately defined DL Multicast Channel(MCH). UL transport channels used to deliver data from a UE to theE-UTRAN include a Random Access Channel (RACH) carrying an initialcontrol message and a UL SCH carrying user traffic or a control message.Logical channels that are defined above transport channels and mapped tothe transport channels include a Broadcast Control Channel (BCCH), aPaging Control Channel (PCCH), a Common Control Channel (CCCH), aMulticast Control Channel (MCCH), a Multicast Traffic Channel (MTCH),etc.

FIG. 2 illustrates physical channels and a general method fortransmitting signals on the physical channels in the 3GPP system.

Referring to FIG. 2, when a UE is powered on or enters a new cell, theUE performs initial cell search (S201). The initial cell search involvesacquisition of synchronization to an eNB. Specifically, the UEsynchronizes its timing to the eNB and acquires a cell Identifier (ID)and other information by receiving a Primary Synchronization Channel(P-SCH) and a Secondary Synchronization Channel (S-SCH) from the eNB.Then the UE may acquire information broadcast in the cell by receiving aPhysical Broadcast Channel (PBCH) from the eNB. During the initial cellsearch, the UE may monitor a DL channel state by receiving a DownLinkReference Signal (DL RS).

After the initial cell search, the UE may acquire detailed systeminformation by receiving a Physical Downlink Control Channel (PDCCH) andreceiving a Physical Downlink Shared Channel (PDSCH) based oninformation included in the PDCCH (S202).

If the UE initially accesses the eNB or has no radio resources forsignal transmission to the eNB, the UE may perform a random accessprocedure with the eNB (S203 to S206). In the random access procedure,the UE may transmit a predetermined sequence as a preamble on a PhysicalRandom Access Channel (PRACH) (S203 and S205) and may receive a responsemessage to the preamble on a PDCCH and a PDSCH associated with the PDCCH(S204 and S206). In the case of a contention-based RACH, the UE mayadditionally perform a contention resolution procedure.

After the above procedure, the UE may receive a PDCCH and/or a PDSCHfrom the eNB (S207) and transmit a Physical Uplink Shared Channel(PUSCH) and/or a Physical Uplink Control Channel (PUCCH) to the eNB(S208), which is a general DL and UL signal transmission procedure.Particularly, the UE receives Downlink Control Information (DCI) on aPDCCH. Herein, the DCI includes control information such as resourceallocation information for the UE. Different DCI formats are definedaccording to different usages of DCI.

Control information that the UE transmits to the eNB on the UL orreceives from the eNB on the DL includes a DL/UL ACKnowledgment/NegativeACKnowledgment (ACK/NACK) signal, a Channel Quality Indicator (CQI), aPrecoding Matrix Index (PMI), a Rank Indicator (RI), etc. In the 3GPPLTE system, the UE may transmit control information such as a CQI, aPMI, an RI, etc. on a PUSCH and/or a PUCCH.

FIG. 3 illustrates a structure of a radio frame used in the LTE system.

Referring to FIG. 3, a radio frame is 10 ms (327200×Ts) long and dividedinto 10 equal-sized subframes. Each subframe is 1 ms long and furtherdivided into two slots. Each time slot is 0.5 ms (15360×Ts) long.Herein, Ts represents a sampling time and Ts=1/(15 kHz×2048)=3.2552×10−8(about 33 ns). A slot includes a plurality of Orthogonal FrequencyDivision Multiplexing (OFDM) symbols or SC-FDMA symbols in the timedomain by a plurality of Resource Blocks (RBs) in the frequency domain.In the LTE system, one RB includes 12 subcarriers by 7 (or 6) OFDMsymbols. A unit time during which data is transmitted is defined as aTransmission Time Interval (TTI). The TTI may be defined in units of oneor more subframes. The above-described radio frame structure is purelyexemplary and thus the number of subframes in a radio frame, the numberof slots in a subframe, or the number of OFDM symbols in a slot mayvary.

FIG. 4 is a diagram illustrating a radio frame structure fortransmitting an SS (synchronization signal) in LTE system. Inparticular, FIG. 4 illustrates a radio frame structure for transmittinga synchronization signal and PBCH in FDD (frequency division duplex).FIG. 4(a) shows positions at which the SS and the PBCH are transmittedin a radio frame configured by a normal CP (cyclic prefix) and FIG. 4(b)shows positions at which the SS and the PBCH are transmitted in a radioframe configured by an extended CP.

An SS will be described in more detail with reference to FIG. 4. An SSis categorized into a PSS (primary synchronization signal) and an SSS(secondary synchronization signal). The PSS is used to acquiretime-domain synchronization such as OFDM symbol synchronization, slotsynchronization, etc. and/or frequency-domain synchronization. And, theSSS is used to acquire frame synchronization, a cell group ID, and/or aCP configuration of a cell (i.e. information indicating whether to anormal CP or an extended is used). Referring to FIG. 4, a PSS and an SSSare transmitted through two OFDM symbols in each radio frame.Particularly, the SS is transmitted in first slot in each of subframe 0and subframe 5 in consideration of a GSM (Global System for Mobilecommunication) frame length of 4.6 ms for facilitation of inter-radioaccess technology (inter-RAT) measurement. Especially, the PSS istransmitted in a last OFDM symbol in each of the first slot of subframe0 and the first slot of subframe 5. And, the SSS is transmitted in asecond to last OFDM symbol in each of the first slot of subframe 0 andthe first slot of subframe 5. Boundaries of a corresponding radio framemay be detected through the SSS. The PSS is transmitted in the last OFDMsymbol of the corresponding slot and the SSS is transmitted in the OFDMsymbol immediately before the OFDM symbol in which the PSS istransmitted. According to a transmission diversity scheme for the SS,only a single antenna port is used. However, the transmission diversityscheme for the SS standards is not separately defined in the currentstandard.

Referring to FIG. 4, by detecting the PSS, a UE may know that acorresponding subframe is one of subframe 0 and subframe 5 since the PSSis transmitted every 5 ms but the UE cannot know whether the subframe issubframe 0 or subframe 5. That is, frame synchronization cannot beobtained only from the PSS. The UE detects the boundaries of the radioframe in a manner of detecting an SSS which is transmitted twice in oneradio frame with different sequences.

Having demodulated a DL signal by performing a cell search procedureusing the PSS/SSS and determined time and frequency parameters necessaryto perform UL signal transmission at an accurate time, a UE cancommunicate with an eNB only after obtaining system informationnecessary for a system configuration of the UE from the eNB.

The system information is configured with a master information block(MIB) and system information blocks (SIBs). Each SIB includes a set offunctionally related parameters and is categorized into an MIB, SIB Type1 (SIB1), SIB Type 2 (SIB2), and SIB3 to SIB8 according to the includedparameters.

The MIB includes most frequently transmitted parameters which areessential for a UE to initially access a network served by an eNB. TheUE may receive the MIB through a broadcast channel (e.g. a PBCH). TheMIB includes a downlink system bandwidth (DL BW), a PHICH configuration,and a system frame number (SFN). Thus, the UE can explicitly knowinformation on the DL BW, SFN, and PHICH configuration by receiving thePBCH. On the other hand, the UE may implicitly know information on thenumber of transmission antenna ports of the eNB. The information on thenumber of the transmission antennas of the eNB is implicitly signaled bymasking (e.g. XOR operation) a sequence corresponding to the number ofthe transmission antennas to 16-bit CRC (cyclic redundancy check) usedin detecting an error of the PBCH.

The SIB1 includes not only information on time-domain scheduling forother SIBs but also parameters necessary to determine whether a specificcell is suitable in cell selection. The UE receives the SIB1 viabroadcast signaling or dedicated signaling.

A DL carrier frequency and a corresponding system bandwidth can beobtained by MIB carried by PBCH. A UL carrier frequency and acorresponding system bandwidth can be obtained through systeminformation corresponding to a DL signal. Having received the MIB, ifthere is no valid system information stored in a corresponding cell, aUE applies a value of a DL BW included in the MIB to a UL bandwidthuntil system information block type 2 (SystemInformationBlockType2,SIB2) is received. For example, if the UE obtains the SIB2, the UE isable to identify the entire UL system bandwidth capable of being usedfor UL transmission through UL-carrier frequency and UL-bandwidthinformation included in the SIB2.

In the frequency domain, PSS/SSS and PBCH are transmitted irrespectiveof an actual system bandwidth in total 6 RBs, i.e., 3 RBs in the leftside and 3 RBs in the right side with reference to a DC subcarrierwithin a corresponding OFDM symbol. In other words, the PSS/SSS and thePBCH are transmitted only in 72 subcarriers. Therefore, a UE isconfigured to detect or decode the SS and the PBCH irrespective of adownlink transmission bandwidth configured for the UE.

Having completed the initial cell search, the UE can perform a randomaccess procedure to complete the accessing the eNB. To this end, the UEtransmits a preamble via PRACH (physical random access channel) and canreceive a response message via PDCCH and PDSCH in response to thepreamble. In case of contention based random access, it may transmitadditional PRACH and perform a contention resolution procedure such asPDCCH and PDSCH corresponding to the PDCCH.

Having performed the abovementioned procedure, the UE can performPDCCH/PDSCH reception and PUSCH/PUCCH transmission as a general UL/DLsignal transmission procedure.

The random access procedure is also referred to as a random accesschannel (RACH) procedure. The random access procedure is used forvarious usages including initial access, UL synchronization adjustment,resource allocation, handover, and the like. The random access procedureis categorized into a contention-based procedure and a dedicated (i.e.,non-contention-based) procedure. In general, the contention-based randomaccess procedure is used for performing initial access. On the otherhand, the dedicated random access procedure is restrictively used forperforming handover, and the like. When the contention-based randomaccess procedure is performed, a UE randomly selects a RACH preamblesequence. Hence, a plurality of UEs can transmit the same RACH preamblesequence at the same time. As a result, a contention resolutionprocedure is required thereafter. On the contrary, when the dedicatedrandom access procedure is performed, the UE uses an RACH preamblesequence dedicatedly allocated to the UE by an eNB. Hence, the UE canperform the random access procedure without a collision with a differentUE.

The contention-based random access procedure includes 4 steps describedin the following. Messages transmitted via the 4 steps can berespectively referred to as message (Msg) 1 to 4 in the presentinvention.

Step 1: RACH preamble (via PRACH) (UE to eNB)

Step 2: Random access response (RAR) (via PDCCH and PDSCH (eNB to)

Step 3: Layer 2/Layer 3 message (via PUSCH) (UE to eNB)

Step 4: Contention resolution message (eNB to UE)

On the other hand, the dedicated random access procedure includes 3steps described in the following. Messages transmitted via the 3 stepscan be respectively referred to as message (Msg) 0 to 2 in the presentinvention. It may also perform uplink transmission (i.e., step 3)corresponding to PAR as a part of the ransom access procedure. Thededicated random access procedure can be triggered using PDCCH(hereinafter, PDCCH order) which is used for an eNB to indicatetransmission of an RACH preamble.

Step 0: RACH preamble assignment via dedicated signaling (eNB to UE)

Step 1: RACH preamble (via PRACH) (UE to eNB)

Step 2: Random access response(RAR) (via PDCCH and PDSCH) (eNB to UE)

After the RACH preamble is transmitted, the UE attempts to receive arandom access response (RAR) in a preconfigured time window.Specifically, the UE attempts to detect PDCCH (hereinafter, RA-RNTIPDCCH) (e.g., a CRC masked with RA-RNTI in PDCCH) having RA-RNTI (randomaccess RNTI) in a time window. If the RA-RNTI PDCCH is detected, the UEchecks whether or not there is a RAR for the UE in PDSCH correspondingto the RA-RNTI PDCCH. The RAR includes timing advance (TA) informationindicating timing offset information for UL synchronization, UL resourceallocation information (UL grant information), a temporary UE identifier(e.g., temporary cell-RNTI, TC-RNTI), and the like. The UE can performUL transmission (e.g., message 3) according to the resource allocationinformation and the TA value included in the RAR. HARQ is applied to ULtransmission corresponding to the RAR. In particular, the UE can receivereception response information (e.g., PHICH) corresponding to themessage 3 after the message 3 is transmitted.

A random access preamble (i.e. RACH preamble) consists of a cyclicprefix of a length of TCP and a sequence part of a length of TSEQ. TheTCP and the TSEQ depend on a frame structure and a random accessconfiguration. A preamble format is controlled by higher layer. The RACHpreamble is transmitted in a UL subframe. Transmission of the randomaccess preamble is restricted to a specific time resource and afrequency resource. The resources are referred to as PRACH resources. Inorder to match an index 0 with a PRB and a subframe of a lower number ina radio frame, the PRACH resources are numbered in an ascending order ofPRBs in subframe numbers in the radio frame and frequency domain. Randomaccess resources are defined according to a PRACH configuration index(refer to 3GPP TS 36.211 standard document). The RACH configurationindex is provided by a higher layer signal (transmitted by an eNB).

In LTE/LTE-A system, subcarrier spacing for a random access preamble(i.e., RACH preamble) is regulated by 1.25 kHz and 7.5 kHz for preambleformats 0 to 3 and a preamble format 4, respectively (refer to 3GPP TS36.211).

FIG. 5 illustrates exemplary control channels included in a controlregion of a subframe in a DL radio frame.

Referring to FIG. 5, a subframe includes 14 OFDM symbols. The first oneto three OFDM symbols of a subframe are used for a control region andthe other 13 to 11 OFDM symbols are used for a data region according toa subframe configuration. In FIG. 5, reference characters R1 to R4denote RSs or pilot signals for antenna 0 to antenna 3. RSs areallocated in a predetermined pattern in a subframe irrespective of thecontrol region and the data region. A control channel is allocated tonon-RS resources in the control region and a traffic channel is alsoallocated to non-RS resources in the data region. Control channelsallocated to the control region include a Physical Control FormatIndicator Channel (PCFICH), a Physical Hybrid-ARQ Indicator Channel(PHICH), a Physical Downlink Control Channel (PDCCH), etc.

The PCFICH is a physical control format indicator channel carryinginformation about the number of OFDM symbols used for PDCCHs in eachsubframe. The PCFICH is located in the first OFDM symbol of a subframeand configured with priority over the PHICH and the PDCCH. The PCFICHincludes 4 Resource Element Groups (REGs), each REG being distributed tothe control region based on a cell Identity (ID). One REG includes 4Resource Elements (REs). An RE is a minimum physical resource defined byone subcarrier by one OFDM symbol. The PCFICH is set to 1 to 3 or 2 to 4according to a bandwidth. The PCFICH is modulated in Quadrature PhaseShift Keying (QPSK).

The PHICH is a physical Hybrid-Automatic Repeat and request (HARQ)indicator channel carrying an HARQ ACK/NACK for a UL transmission. Thatis, the PHICH is a channel that delivers DL ACK/NACK information for ULHARQ. The PHICH includes one REG and is scrambled cell-specifically. AnACK/NACK is indicated in one bit and modulated in Binary Phase ShiftKeying (BPSK). The modulated ACK/NACK is spread with a Spreading Factor(SF) of 2 or 4. A plurality of PHICHs mapped to the same resources forma PHICH group. The number of PHICHs multiplexed into a PHICH group isdetermined according to the number of spreading codes. A PHICH (group)is repeated three times to obtain a diversity gain in the frequencydomain and/or the time domain.

The PDCCH is a physical DL control channel allocated to the first n OFDMsymbols of a subframe. Herein, n is 1 or a larger integer indicated bythe PCFICH. The PDCCH occupies one or more CCEs. The PDCCH carriesresource allocation information about transport channels, PCH andDL-SCH, a UL scheduling grant, and HARQ information to each UE or UEgroup. The PCH and the DL-SCH are transmitted on a PDSCH. Therefore, aneNB and a UE transmit and receive data usually on the PDSCH, except forspecific control information or specific service data.

Information indicating one or more UEs to receive PDSCH data andinformation indicating how the UEs are supposed to receive and decodethe PDSCH data are delivered on a PDCCH. For example, on the assumptionthat the Cyclic Redundancy Check (CRC) of a specific PDCCH is masked byRadio Network Temporary Identity (RNTI) “A” and information about datatransmitted in radio resources (e.g. at a frequency position) “B” basedon transport format information (e.g. a transport block size, amodulation scheme, coding information, etc.) “C” is transmitted in aspecific subframe, a UE within a cell monitors, that is, blind-decodes aPDCCH using its RNTI information in a search space. If one or more UEshave RNTI “A”, these UEs receive the PDCCH and receive a PDSCH indicatedby “B” and “C” based on information of the received PDCCH.

FIG. 6 illustrates a structure of a UL subframe in the LTE system.

Referring to FIG. 6, a UL subframe may be divided into a control regionand a data region. A Physical Uplink Control Channel (PUCCH) includingUplink Control Information (UCI) is allocated to the control region anda Physical uplink Shared Channel (PUSCH) including user data isallocated to the data region. The middle of the subframe is allocated tothe PUSCH, while both sides of the data region in the frequency domainare allocated to the PUCCH. Control information transmitted on the PUCCHmay include an HARQ ACK/NACK, a CQI representing a downlink channelstate, an RI for Multiple Input Multiple Output (MIMO), a SchedulingRequest (SR) requesting UL resource allocation. A PUCCH for one UEoccupies one RB in each slot of a subframe. That is, the two RBsallocated to the PUCCH are frequency-hopped over the slot boundary ofthe subframe. Particularly, PUCCHs with m=0, m=1, and m=2 are allocatedto a subframe in FIG. 6.

Hereinafter, channel state information (C SI) reporting will bedescribed below. In the current LTE standard, there are two MIMOtransmission schemes, open-loop MIMO operating without channelinformation and closed-loop MIMO operating with channel information.Particularly in the closed-loop MIMO, each of an eNB and a UE mayperform beamforming based on CSI to obtain the multiplexing gain of MIMOantennas. To acquire CSI from the UE, the eNB may command the UE to feedback CSI on a downlink signal by allocating a PUCCH(Physical UplinkControl CHannel) or a PUSCH(Physical Uplink Shared CHannel) to the UE.

The CSI is largely classified into three information types, RI (RankIndicator), PMI (Precoding Matrix), and CQI (Channel QualityIndication). First of all, the RI indicates rank information of achannel as described above, and means the number of streams that may bereceived by a UE through the same time-frequency resources. Also, sincethe RI is determined by long-term fading of a channel, the RI may be fedback to an eNB in a longer period than a PMI value and a CQI value.

Second, the PMI is a value obtained by reflecting spatialcharacteristics of a channel, and indicates a precoding matrix index ofan eNB, which is preferred by the UE based on a metric such as signal tointerference and noise ratio (SINR). Finally, the CQI is a valueindicating channel strength, and generally means a reception SINR thatmay be obtained by the eNB when the PMI is used.

In the 3GPP LTE-A system, the eNB may configure a plurality of CSIprocesses for the UE, and may be reported CSI for each of the CSIprocesses. In this case, the CSI process includes CSI-RS resource forspecifying signal quality and CSI-IM (interference measurement)resource, that is, IMR (interference measurement resource) forinterference measurement.

Since a wavelength becomes short in the field of Millimeter Wave (mmW),a plurality of antenna elements may be installed in the same area. Inmore detail, a wavelength is 1 cm in a band of 30 GHz, and a total of64(8×8) antenna elements of a 2D array may be installed in a panel of 4by 4 cm at an interval of 0.5 lambda(wavelength). Therefore, a recenttrend in the field of mmW attempts to increase coverage or throughput byenhancing BF (beamforming) gain using a plurality of antenna elements.

In this case, if a transceiver unit (TXRU) is provided to control atransmission power and phase per antenna element, independentbeamforming may be performed for each frequency resource. However, aproblem occurs in that effectiveness is deteriorated in view of costwhen TXRU is provided for all of 100 antenna elements. Therefore, ascheme is considered, in which a plurality of antenna elements aremapped into one TXRU and a beam direction is controlled by an analogphase shifter. Since this analog beamforming scheme may make only onebeam direction in a full band, a problem occurs in that frequencyselective beamforming is not available.

As an intermediate type of digital BF and analog BF, a hybrid BF havingB TXRUs smaller than Q antenna elements may be considered. In this case,although there is a difference depending on a connection scheme of BTXRUs and Q antenna elements, the number of beam directions that enablesimultaneous transmission is limited to B or less.

FIG. 7 illustrates examples of a connection scheme between TXRUs andantenna elements.

(a) of FIG. 7 illustrates that TXRU is connected to a sub-array. In thiscase, the antenna elements are connected to only one TXRU. Unlike (a) ofFIG. 7, (b) of FIG. 7 illustrates that TXRU is connected to all antennaelements. In this case, the antenna elements are connected to all TXRUs.In FIG. 7, W indicates a phase vector multiplied by an analog phaseshifter. That is, a direction of analog beamforming is determined by W.In this case, mapping between CSI-RS antenna ports and TXRUs may be1-to-1 or 1-to-many.

As more communication devices require greater communication capacity,the need of mobile broadband communication more advanced than theconventional RAT (radio access technology) has been issued. Also,massive MTC (Machine Type Communications) technology that providesvarious services anywhere and at any time by connecting a plurality ofdevices and things is one of main issues which will be considered innext generation communication. Furthermore, a communication systemdesign considering service/UE susceptible to reliability and latency hasbeen discussed. Considering this status, the introduction of the nextgeneration RAT has been discussed, and the next generation RAT will bereferred to as NewRAT in the present invention.

A self-contained subframe structure shown in FIG. 8 is considered in thefifth generation NewRAT to minimize data transmission latency in a TDDsystem. FIG. 8 illustrates an example of a self-contained subframestructure.

In FIG. 8, oblique line areas indicate downlink control regions andblack colored areas indicate uplink control regions. Areas having nomark may be used for downlink data transmission or uplink datatransmission. In this structure, downlink transmission and uplinktransmission are performed in due order within one subframe, wherebydownlink data may be transmitted and uplink ACK/NACK may be receivedwithin the subframe. As a result, the time required for datare-transmission may be reduced when an error occurs in datatransmission, whereby latency of final data transfer may be minimized.

In this self-contained subframe structure, a time gap for switching froma transmission mode to a reception mode or vice versa is required forthe eNB and the UE. To this end, some OFDM symbols (OS) at the time whena downlink is switched to an uplink in the self-contained subframestructure are set to a guard period.

Examples of the self-contained subframe type that may be configured inthe system operating based on the NewRAT may consider four subframetypes as follows.

-   -   downlink control period+downlink data period+GP+uplink control        period    -   downlink control period+downlink data period    -   downlink control period+GP+uplink data period+uplink control        period    -   downlink control period+GP+uplink data period

In the present invention, a method of configuring a synchronizationsignal for a Bandwidth Part (BWP), in which Remaining Minimum SystemInformation (RMSI) does not exist, on a network supportive of the 5G NewRAT (NR) system is described as follows. In some implementations of thepresent invention, RMSI may be interpreted as a System Information Block1 (SIB1) and include system information a UE should obtain afterreception of a Master System Information Block (MIB) through NR-PBCH(Physical Broadcast Channel).

In order to increase total signal throughput, a system supportive of NRcan define a wideband system of hundreds of MHz considerably wide incomparison with the legacy LTE system. In this case, a base station canconfigure an assigned wideband frequency with a single Component Carrier(CC) in order to use an assigned frequency as efficient as possible.Yet, on account of a cost price for manufacturing a UE, a usage of a UEand the like, a maximum frequency bandwidth supportable by a UE can bediversified. For this reason, the UE may not be able to cover the wholebandwidth assigned to the base station. Namely, a maximum frequencybandwidth supportable by the UE may be possibly smaller than the wholebandwidth assigned to the base station.

Therefore, in order to efficiently support a system, an NR systeminforms each UE of a frequency bandwidth and a frequency band positionand the corresponding UE will operate based on a maximum frequencybandwidth supportable by a UE. And, the UE operates on the correspondingfrequency band. In this case, a base station transmits a mobilityReference Signal (RS) defined for mobility support of the UE through afrequency band assigned to the UE, thereby supporting UE's mobilitysmoothly. For example, in case of NR, an SS block is basically definedas a mobility RS and a CSI-RS can be utilized as a mobility RSadditionally if necessary.

Generally, a Synchronization Signal Block (SSB) is used for the usage ofan initial access. Namely, a UE performing an access detects a cellusing a PSS and a SSS in an SSB, and then obtains information foraccessing a system by receiving System Information (SI) on the detectedcell.

In case of an NR system, SI may be classified into Minimum SystemInformation transmitted on NR-PBCH, Remaining System Information (RMSI)transmitted on PDSCH, and Other System Information (OSI). Here, theMinimum System Information transmitted on NR-PBCH may be interpreted asa Master System Information Block (MIB).

Generally, a UE detects an SSB and then determines that a cell isdetected only if receiving Minimum System Information through NR-PBCH.Therefore, the NR system defines all PSS, SSS, and PBCH as SSB andstipulates that PSS, SSS and PBCH must be sent together for SSBtransmission.

Meanwhile, as described above, in case of a base station supportive ofbroadband, an NR service should be supported on various bands for UEssupportive of a bandwidth narrower than a bandwidth supportable by thebase station. Namely, a multitude of SSBs can be transmitted within asingle system band supported by the base station.

In this case, if an initial access is allowed for all SSB transmittedbands, the base station should transmit RMSI and OSI on all the SSBtransmitted bands. Yet, unless there are numerous UEs attempting theinitial access, if the RMSI and OSI transmitted on all bands, iteventually works as an overhead of a system. Particularly, since a beamsweeping for a broadcast message on a ultrahigh frequency band such as amillimeter band should be performed in all beam directions, it causes aproblem that system overhead increases in proportion to the number ofbeams supported by the base station.

On the other hand, if a base station transmits an SSB only but does nottransmit RMSI or OSI in order to decrease system overhead, it causes aproblem that a UE attempting an initial access detects the SSB and thenattempts an initial access consistently to receive RMSI and OSIcorresponding to the SSB.

For example, referring to FIG. 9, in case of a UE1 and a UE3, since abase station transmits SSB and RMSI together within a band assigned forthe UE1 and UE3, each of the UE1 and UE3 can succeed in an initialaccess in a manner of detecting the SSB and then receiving the RMSI. Onthe other hand, in case of a UE2, despite that the base stationtransmits an SSB only within a band assigned for the UE2 but does nottransmit RMSI, the UE detects the SSB and then continues to attempt toreceive RMSI through the SSB. Thus, it may cause a problem that the UE2fails in an initial access.

To solve such a problem, the present invention intends to propose amethod for a UE attempting an initial access (i.e., a UE attempting afrequency scan for determining a presence or non-presence of RMSI bychanging a frequency band) to operate in a manner of distinguishing anaccessible band corresponding to a frequency band allowing an initialaccess and a non-accessible band corresponding to a frequency band notallowing an initial access from each other.

Particularly, the present invention intends to propose the two solutionsin the following as solutions for the above-described problem.

-   -   By preventing cell detection through an SSB, a UE cannot stay on        a frequency band not supporting an initial access. Namely, a UE        is made not to receive RMSI consistently on a non-accessible        band.    -   Despite detecting an SSB, a UE is made to recognize that it is        unable to attempt an initial access on an SSB detected frequency        band. Namely, the UE is made to recognize that the SSB detected        frequency band is a non-accessible band.

The above-proposed two solutions are described in detail as follows.

<1. A Method for Preventing a Success in Detection of SSB>

1-1. A Method of Defining a PSS Sequence or an SSS Sequence DifferentlyAccording to a Band

By defining a PSS sequence or an SSS sequence differently according toan accessible band or a non-accessible band, a UE attempting an initialaccess is made to fail in detection of an SSB. A detailed method ofdifferently defining a PSS or SSS sequence according to a band isdescribed as follows.

-   -   By defining PSS or SSS sequences of an accessible band and a        non-accessible band differently, a UE is enabled to detect an        SSB on the accessible band only.    -   A rule for mapping a PSS or SSS sequence to a Resource Element        (RE) can be changed according to a band. For example, on a        non-accessible band, a sequence is mapped to an RE in a reverse        form or a sequence mapping method can be differentiated per        band.

Moreover, the above-described method is applicable to one or both of aPSS and an SSS. Yet, if a non-accessible band assigned UE accessed asystem already, the UE may be informed that the assigned band is anon-accessible band and instructed to detect an SSB using a PSS/SSSsequence different from that in attempting an initial access on anaccessible band.

1.2. Method of Defining a Sequence Mapping Method Differently Accordingto a Cell ID

Generally, information on a cell ID is obtained through a PSS and anSSS. Particularly, in case of an NR system, a prescribed PSS ID isobtained from 3 PSS IDs through a PSS sequence and an SSS IDcorresponding to a received SSS sequence is obtained using the PSS IDand timing information. And, a cell ID is obtained through the obtainedPSS and SSS IDs.

In this case, a hypothesis for the SSS ID detection is determined from aPSS ID. Hence, by differentiating a hypothesis for an SSS ID mapped to aPSS ID according to an accessible band or a non-accessible band, a UEattempting an initial access can be prevented from cell detectionthrough an SSB of the non-accessible band. For example, if an SSS ID ofan accessible band has hypothetic values ranging from 0 to 336, an SSIDof a non-accessible band can be configured to have values ranging from337 to 673.

Yet, after a UE having a non-accessible band assigned thereto accessed asystem already, the UE can be informed that the assigned band is anon-accessible band and instructed to detect an SSB using a cell IDmapping rule different from that in case of attempting an initial accesson an accessible band.

1-3. Method of Defining a Position of an SSS Differently with Referenceto a PSS

LTE or NT system defines positions of PSS and SSS in a single slot.Namely, having obtained information on a reception (Rx) position of aPSS within an SSB though the PSS, a UE may assume a position at which anSSS will be received and attempt detection of the SSS at the assumedposition.

Hence, by preventing a UE from receiving an SSS on a non-accessible bandin a manner of differently assigning a position of an SSS with referenceto a PSS in an SSB of a non-accessible band and a position of an SSSwith reference to a PSS in an SSSB of an accessible band, it is able tomake the UE fail in cell detection. For example, if a configuration ofan SSB of an accessible band is in order of PSS-PBCH-SSS-PBCH, aconfiguration of an SSB of a non-accessible band can be set in order ofSSS-PBCH-PSS-PBCH. Namely, by changing a position of an SSS withreference to a PSS, the UE is prevented from succeeding in celldetection on a non-accessible band.

Yet, after a UE having a non-accessible band assigned thereto accessed asystem already, the UE can be informed that the assigned band is anon-accessible band and instructed to detect an SSB using symbolpositions of PSS and SSS different from those in case of attempting aninitial access on an accessible band.

1-4. Method of Changing a Frequency Position of an SSB

In case that a UE performs a frequency scan on a random band, a networkmay generally share a position of an SSB transmittable frequency withthe UE in advance in order to help the UE obtain a presence ornon-presence of a system through detection of the SSB. Here, theposition of the SSB transmittable frequency can be named a sync rasterand a sync raster defined between the network and the UE may be definedin the standard document. Namely, the sync raster can be agreed betweenthe network and the UE in advance and defined in the standard document.

And, the UE performing the frequency scan performs a detection of an SSBat a sync raster shared in advance only. Hence, if an SSB is transmittedat a frequency that is not a sync raster shared between the network andthe UE in advance, the UE attempting an initial access cannot succeed inSSB detection. Using this method, a wideband base station can transmitan SSB of a non-accessible band through a frequency that is not definedas an accessible sync raster for an accessible band.

Yet, after a UE having a non-accessible band assigned thereto accessed asystem already, the UE should be informed of a transmission (Tx)position of the SSB on the non-accessible band. Namely, it can beindicated that the sync raster of the non-accessible band is spacedapart in a predetermined frequency offset from a position of theaccessible sync raster of the accessible band. Here, the predeterminedfrequency offset may be shared between the network and the UE in advanceor indicated by a base station. On the other hand, there may be a methodfor a base station to designate a sync raster, which is not anaccessible sync raster of an accessible band, to a UE.

Using the above-described 4 kinds of methods, if the success in thedetection of SSB is prevented, a base station should inform a UE of bandinformation for a neighbor cell to measure a neighbor cell or inform theUE that a band currently assigned to the UE is common to all cells. Forexample, if a band currently assigned to a UE is an accessible band, itshould be indicated that it is an accessible band in a neighbor cell aswell, If a band assigned to a UE is a non-accessible band, it should beindicated that it is a non-accessible band in a neighbor cell as well.

<2. Method of Indicating that a Band Succeeding in SSB Detection is nota Carrier for an Initial Access>

Meanwhile, if an SSB is prevented from being detected, according to aUE's implementation algorithm and a configuration method of an SSB for anon-accessible band, a UE may attempt SSB detection for a long time,thereby causing a problem that a time for a frequency scan increases.

To solve the above-described problem, proposed in the following is amethod of indicating that an SSB detected frequency band is anon-accessible band through information relevant to the SSB.

2.1. Method of Indicating a Non-Accessible Band Through an SSB TimeIndex

In an NR system, a multitude of SSBs can be transmitted at a singlefrequency for a multi-beam transmission. In doing so, an SSB time indexfor indicating where an SSB is located within a single frame can betransmitted through the SSB.

Hence, in order to inform a UE that an SSB detected band is anon-accessible band, an SSB time index for an accessible band and an SSBtime index for a non-accessible band can be defined separately. Namely,when a UE performing an initial access detects an SSB, if an SSB timeindex obtained through the detected SSB is not a value corresponding toan accessible band, the UE recognizes that an SSB detected frequency isa non-accessible band, thereby stopping an access attempt to a system onthe corresponding frequency.

For detailed example, if an SSB time index value of an accessible bandis configured to have an odd number value (e.g., 1, 3, 5 . . . ) only,an SSB time index value of a non-accessible band can be configured tohave an even number value (e.g., 2, 4, 6 . . . ). If a time index of anSSB detected by a UE is an odd number value, the UE may determine thatan SSB detected frequency is an accessible band. If the time index ofthe SSB is an even number value, the UE may determine that an SSBdetected frequency is a non-accessible band.

2-2. Method of Indicating a Non-accessible Band Using PBCH DM-RS

In an NR system, PBCH is transmitted within an SSB and PBCH DM-RS isdefined for channel estimation for PBCH reception. PBCH DM-RS isconfigured in a manner of defining a scrambling sequence including cellID information at least for inter-cell classification and using thescrambling sequence.

Hence, in order to inform a UE that an SSB detected band is anon-accessible band, a scrambling sequence of PBCH DM-RS for anaccessible band and a scrambling sequence of PBCH DM-RS for anon-accessible band can be defined differently. Namely, a UE performingan initial access can determine whether an SSB detected through a blinddecoding for PBCH DM-RS is transmitted on an accessible band or anon-accessible band.

2-3. Method of Indicating a Non-accessible Band Using PBCH Information

In case that a UE attempts an access to a system, the UE obtainsinformation on a slot and frame boundary and cell ID information using aSynchronization Signal (SS) within an SSB. Thereafter, as a firstprocess for obtaining System Information (SI), an operation of obtainingMinimum System Information (i.e., MIB) through PBCH is performed. In anNR system, a Super Frame Number (SFN), an SSB time index, schedulinginformation of RMSI and the like are obtained through Minimum SystemInformation.

In this case, since System Information (SI) such as RMSI and the like isnot transmitted on a non-accessible band basically, it is not necessaryto transmit the scheduling information of the RMSI. Hence, using a bitfield that delivers RMSI scheduling information unused on thenon-accessible band, it is able to deliver information of an accessiblesync raster. Namely, using a bit field delivering RMSI schedulinginformation, it is able to deliver information relevant to an SSBtransmitted raster within an accessible band.

Having received the accessible sync raster information, a UE candirectly move to the SSB transmitted raster of the accessible band. Thisis referred to as sync redirection. Through this, the UE can perform afrequency scan quickly.

In some implementations, information on an accessible sync raster may beindicated as a relative position from a current position in a syncraster currently scanned by a UE, or an absolute position of theaccessible sync raster. For example, if information on an accessiblesync raster is indicated as a relative position to a sync rastercurrently scanned by a UE, a specified frequency offset value isindicated with reference to the sync raster currently scanned by the UE,whereby a sync redirection to a sync raster indicated by the frequencyoffset value from the currently scanned sync raster is performed so asto enable a frequency scan to be performed at the corresponding syncraster.

Meanwhile, in order to perform the sync redirection, it is able todefine a 1-bit field to distinguish whether a bit field for RMSIscheduling information actually includes the RMSI scheduling informationor information for the sync redirection.

In some implementations, if the information for the RMSI schedulingindicates a specific bit or value, it is able to indicate that an SSB ofan accessible band is not transmitted within a prescribed frequencyrange, i.e., a predetermined sync raster range. So to speak, if theinformation for the RMSI scheduling indicates a specific bit or value,it is able to indicate that an accessible band does not exist within apredetermined sync raster range.

To be more specific about the above description, when a UE performs aninitial access, the UE can attempt an initial access through anon-accessible band on which an RMSI non-existing SSB is located and‘absence of RMSI in the corresponding band’ can be delivered to the UEthrough PBCH MIB. After ‘absence of RMSI’ has been delivered to the UE,the UE should discover a position of an accessible band on which an RMSIexisting SSB is transmitted. Although an SSB frequency position of anaccessible band can be discovered by sequentially performing PBCHdecoding according to SS_PBCH_frequency position that defines frequencypositions of SSB in RAN4, if a non-accessible band is accessedcontiguously, the UE may repeat a frequency scan process for a longtime. Hence, for an efficient operation, the UE can be informed offrequency positions of an RMSI existing SSB. According to RAN4,frequency positions of an SSB can be defined as a function of a lowestfrequency position of an NR operating band, a multiple of a sync raster,and a raster offset. For example, an LTE re-farming band reusing an LTEband is defined as {N*900 kHz+M*5 kHz}, an FR1 band meaning a band below6 GHz of NR is defined as {2400 MHz+N*1.44 MHz},and an FR2 band meaninga band above 6 GHz of NR is defined as {[24250.08] MHz+N*[17.28] MHz}.In this case, specific values of M and N may follow Table 1 in thefollowing.

Meanwhile, since RMSI corresponding to an SSB does not exist on anon-accessible band, 8 bits defined in PBCH MIB for RMSI CORESETconfiguration are not used. Hence, the 8 bits for the RMSI CORESETconfiguration can be used as an indicator indicating a frequencyposition of an SSB transmitted on an RMSI existing band, i.e., anaccessible band. In NR, since the number and spacing of SSBstransmittable on a specific frequency band are defined differently perdefined band, it is necessary to design that a frequency position of anSSB transmitted on an accessible band can be indicated in considerationof such definition.

So to speak, a frequency position of SSB defined per band can be definedas Table 1, and a frequency position of an RMSI existing SSB per bandcan be indicated according to ‘embodiments 1 to 8’ in the following.

TABLE 1 NR Operating Band SS Block SCS Mini channel BW Number of SSentry/Lowest sync raster n1 15 kHz 5 MHz 2109.9 MHz + 0.9*N + M*5 kHz, N= 0:63, M = −1, 0, or 1 n2 15 kHz 5 MHz 1929.9 MHz + 0.9*N + M*5 kHz, N= 0:63, M = −1, 0, or 1 n3 15 kHz 5 MHz 1804.8 MHz + 0.9*N + M*5 kHz, N= 0:80, M = −1, 0, or 1 n5 15 kHz 5 MHz 868.8 MHz + 0.9*N + M*5 kHz, N =0:25, M = −1, 0, or 1 15 kHz 10 MHz 868.8 MHz + 0.9*6*N + M*5 kHz, N =0:3, M = −1, 0, or 1 30 kHz 10 MHz 873.3 MHz + 0.9*6*N + M*5 kHz, N =0:1, M = −1, 0, or 1 n7 15 kHz 5 MHz 2620.2 MHz + 0.9*N + M*5 kHz, N =0:74, M = −1, 0, or 1 n8 15 kHz 5 MHz 924.6 MHz + 0.9*N + M*5 kHz, N =0:36, M = −1, 0, or 1 n20 15 kHz 5 MHz 790.5 MHz + 0.9*N + M*5 kHz, N =0:31, M = −1, 0, or 1 n28 15 kHz 5 MHz 758.1 MHz + 0.9*N + M*5 kHz, N =0:47, M = −1, 0, or 1 n38 15 kHz 5 MHz 2569.8 MHz + 1.44*N, N = 0:35 n4115 kHz 5 MHz 2496 MHz + 1.44*N, N = 0:131 15 kHz 10 MHz 2496 MHz +1.44*3*N, N = 0:43 30 kHz 10 MHz 2496 MHz + 1.44*N, N = 0:131 n50 15 kHz5 MHz 1432.2 MHz + 0.9*N + M*5 kHz, N = 0:91, M = −1, 0, or 1 n51 15 kHz5 MHz 1426.8 MHz + 0.9*N + M*5 kHz, N = 0:2, M = −1, 0, or 1 n66 15 kHz5 MHz 2109.9 MHz + 0.9*N + M*5 kHz, N = 0:97, M = −1, 0, or 1 15 kHz 10MHz 2109.9 MHz + 0.9*6*N + M*5 kHz, N = 0:15, M = −1, 0, or 1 30 kHz 10MHz 2195.1 MHz + 0.9*6*N + M*5 kHz, N = 0:14, M = −1, 0, or 1 n70 15 kHz5 MHz 1994.7 MHz + 0.9*N + M*5 kHz, N = 0:25, M = −1, 0, or 1 n71 15 kHz5 MHz 616.8 MHz + 0.9*N + M*5 kHz, N = 0:36, M = −1, 0, or 1 n74 15 kHz5 MHz 1474.5 MHz + 0.9*N + M*5 kHz, N = 0:45, M = −1, 0, or 1 n75 15 kHz5 MHz 1432.2 MHz + 0.9*N + M*5 kHz, N = 0:91, M = −1, 0, or 1 n76 15 kHz5 MHz 1426.8 MHz + 0.9*N + M*5 kHz, N = 0:2, M = −1, 0, or 1 n77 30 kHz10 MHz 3300 MHz + 1.44*N, N = 0:619 n78 30 kHz 10 MHz 3300 MHz + 1.44*N,N = 0:341 n79 30 kHz 40 MHz 4400 MHz + 1.44*21*N, N = 0:16 n258 120 kHz50 MHz 24250.08 MHz + N*17.28 MHz, N = 0:186 n257 120 kHz 50 MHz26513.76 MHz + N *17.28 MHz, N = 0:170 240 kHz 100 MHz 26548.32 MHz + 2*N *17.28 MHz, N = 0:83 n260 120 kHz 50 MHz 37002.72 MHz + N *17.28 MHz,N = 0:171 240 kHz 100 MHz 34773.6 MHz + 2* N *17.28 MHz, N = 0:83

(1) Embodiment 1

A reference frequency position of SSB is determined per band defined tobe used in NR, and a frequency position of an RMSI existing SSB from thereference frequency position can be indicated as a relative value. Inthis case, if 8 bits are used, total 256 SSB frequency positions withina band can be indicated.

Meanwhile, if a frequency position of an RMSI existing SSB does notexist in 256 SSB frequency positions that can be indicated using 8 bits,it is necessary to indicate a frequency position of the RMSI existingSSB to a UE through additional signaling. Particularly, since a band n77and a band n78 have 620 SSB transmittable frequency positions (possibleSS_PBCH_frequency positions) and 342 SSB transmittable frequencypositions, respectively, it is unable to indicate all SSB frequencypositions using 256. Hence, in this case, using spare states amongstates that can be indicated using bits for PRB grid offset included inPBCH content, i.e., PBCH MIB, it is able to additionally define anindication of an RMSI existing frequency position.

For example, since 24 PRB grid offsets are indicated on a band FR1 using5 bits, maximum 8 states can be additionally defined. Since 12 PRB gridoffsets are indicated on a band FR2 using 4 bits, maximum 4 states canbe additionally defined. Thereafter, a UE can be aware of a frequencyposition of an RMSI existing SSB from a specific reference point (e.g.,0, 256, or 512) according to an indicated state among the additionallydefined states using 8 bits.

Moreover, when a frequency position of an RMSI existing SSB does notexist within a specific band, if such a fact is additionally signaled toa UE, the UE can attempt to discover the frequency position of the RMSIexisting SSB by moving to another band. Through this process, it is ableto reduce the UE's unnecessary repetition of a frequency scan.Meanwhile, the definitions of the additionally defined states aredescribed as follows.

-   -   First state: RMSI does not exist within a corresponding band    -   Second state: RMSI does not exist at a corresponding sync        raster. A relative value of a frequency position of an RMSI        existing SSB from a reference frequency position defined by 8        bits ranges from 0 to 255.    -   Third state: RMSI does not exist at a corresponding sync raster.        A relative value of a frequency position of an RMSI existing SSB        from a reference frequency position defined by 8 bits ranges        from 256 to 511.    -   Fourth state: RMSI does not exist at a corresponding sync        raster. A relative value of a frequency position of an RMSI        existing SSB from a reference frequency position defined by 8        bits ranges from 512 to 767.

(2) Embodiment 2

A reference frequency position of an SSB is determined per band definedto be used in NR and a frequency position of an RMSI existing SSB fromthe reference frequency position can be signaled as a relative value. Inthis case, if 8 bits are used, it is able to indicate total 256 SSBfrequency positions within a band.

Meanwhile, for a UE's efficient operation, it is not necessary toindicate a case that a frequency position of an RMSI existing SSB doesnot exist within a band. The corresponding indication may use a state ofone of 8 bits for signaling a frequency position of SSB. And, in thiscase, the number of states for signaling a frequency position of SSBbecomes 255. Namely, the state of the 1 bit may include the followings.

-   -   First state: RMSI does not exist within a corresponding band

Yet, there may occur a case that it is unable to indicate frequencyS_PBCH_frequency positions of all SSBs within a specific band using 8bits.

For example, since a band n77 and a band n78 have 620 SSB transmittablefrequency positions (possible SS_PBCH_frequency positions) and 342 SSBtransmittable frequency positions, respectively, it is unable toindicate all SSB frequency positions using 255. Hence, additionalsignaling for indicating this is necessary. And, using spare statesamong states that can be indicated using bits for PRB grid offsetincluded in PBCH content, i.e., PBCH MIB, it is able to additionallydefine an indication of an RMSI existing frequency position.

For example, since 24 PRB grid offsets are indicated on a band FR1 using5 bits, maximum 8 states can be additionally defined. Since 12 PRB gridoffsets are indicated on a band FR2 using 4 bits, maximum 4 states canbe additionally defined. And, a UE can be aware of a frequency positionof an RMSI existing SSB from a specific reference point according to anindicated state using 8 bits.

-   -   First state: RMSI does not exist at a corresponding sync raster.        A relative value of a frequency position of an RMSI existing SSB        from a reference frequency position defined by 8 bits ranges        from 0 to 254.    -   Second state: RMSI does not exist at a corresponding sync        raster. A relative value of a frequency position of an RMSI        existing SSB from a reference frequency position defined by 8        bits ranges from 255 to 509.    -   Third state: RMSI does not exist at a corresponding sync raster.        A relative value of a frequency position of an RMSI existing SSB        from a reference frequency position defined by 8 bits ranges        from 510 to 764.

A UE can be aware of a frequency position of an RMSI existing SSB usingrelative values of 255 SSB frequency positions represented as 8 bitsfrom a reference point (0, 255 or 510) defined according to a state.Moreover, if a UE receives an indication of a state that a frequencyposition of an RMSI existing SSB does not exist within a specific band,the UE can attempt to discover the frequency position of the RMSIexisting SSB by moving to another band. Through this process, it is ableto reduce the UE's unnecessary repetition of a frequency scan.

(3) Embodiment 3

A position currently accessed by a UE is determined as a referencefrequency position, and a frequency position of an RMSI existing SSBfrom the reference frequency position can be signaled as a relativevalue. If 8 bits are used, it is possible to indicate total 256 relativeSSB frequency positions. In this case, an indication range can beconfigured in a low or high frequency position direction from a currentfrequency position (i.e., a reference frequency position) [e.g.,N=−127˜+128] or in a single direction [e.g., N=0˜255]. If an indicationrange is configured in a single direction, all UEs have the samefrequency scan direction in case of an initial access, which can bedefined in the standard document.

Meanwhile, for an efficient operation of a UE, it is necessary toindicate a case that there is no single frequency position of an RMSIexisting SSB within a range that can be currently indicated. In thepresent embodiment, such an indication may use one of 256 states using 8bits to signal an SSB frequency position. In this case, the number ofstates for signaling a frequency position of SSB amounts to 255.

-   -   First state: RMSI does not exist within a corresponding        indication range.

If a UE is aware that RMSI does not exist within a correspondingindication range, the UE can discover a frequency position of an RMSIexisting SSB by starting a frequency scan again from a frequencyposition located at the very end among frequency positions that can beindicated by the indication range. If the indication range includes bothdirections, the UE moves to one of both ends. And, whether to move towhich one of both ends can be signaled using an additional state. If theindication range includes a single direction, the UE can move to an endof the corresponding direction and perform a frequency scan. Hence, ifthe indication range includes both directions, the above-described stateindicating ‘RMSI does not exist within a corresponding indication range’can be changed as follows.

-   -   First state: RMSI does not exist within a corresponding        indication range. Move to a lowest frequency position in the        indication range.    -   Second state: RMSI does not exist within a corresponding        indication range. Move to a highest frequency position in the        indication range.

Moreover, if it is intended to inform a UE that a frequency position ofan RMSI existing SSB is located within a frequency range greater than afrequency range corresponding to the indication range, additionalsignaling for indicating such information is required. And, it is ableto inform the UE of a frequency position of an RMSI existing SSB locatedwithin a frequency range greater than a frequency range corresponding tothe indication range using spare states among the states that can beindicated using bits for PRB grid offset included in a PBCH content,i.e., a PBCH MIB.

For example, since 24 PRB grid offsets are indicated using 5 bits on aband FR1, maximum 8 states can be additionally defined. Since 12 PRBgrid offsets are indicated using 4 bits on a band FR2, maximum 4 statescan be additionally defined. If an indication range is configured in asingle direction, the additionally defined state(s) can be representedas follows. In the following, K indicates a value corresponding to afrequency range greater than a frequency range corresponding to theindication range.

-   -   First state: RMSI does not exist at a corresponding sync raster,        and K is 0.    -   Second state: RMSI does not exist at a corresponding sync        raster, and K is 255.    -   Third state: RMSI does not exist at a corresponding sync raster,        and K is 510.

Namely, in case of using the above-described method, if a currentlocation of a UE and a value for an indication range indicated with 8bits are set to O and N (0˜255), respectively, an indicated frequencyposition

can be expressed asIndicated position=O+N+K.

Yet, if an indication range is configured in both directions, theadditionally defined state(s) can be represented as follows.

-   -   First state: RMSI does not exist at a corresponding sync raster,        and K is 0.    -   Second state: RMSI does not exist at a corresponding sync        raster, and K is −127 or 127, where a sign of K is equal to that        of N.    -   Third state: RMSI does not exist at a corresponding sync raster,        and K is −254 or 254, where a sign of K is equal to that of N.

Namely, if a current location of a UE and a value indicated with 8 bitsare set to O and N (−127˜127), respectively, an indicated frequencyposition

can be expressed asIndicated position=O+N+K.

(4) Embodiment 4

A position currently accessed by a UE is set as a reference frequencyposition, and it is able to signal a frequency position of an RMSIexisting SSB from the reference frequency position as a relative value.If 8 bits are used, it is possible to indicate total 256 relative SSBfrequency positions. In this case, an indication range can be configuredin a low or high frequency position direction from a current frequencyposition (i.e., a reference frequency position) [e.g., N=−127˜+128] orin a single direction [e.g., N=0˜255]. If an indication range isconfigured in a single direction, all UEs have the same frequency scandirection in case of an initial access, which can be defined in thestandard document.

Meanwhile, for an efficient operation of a UE, it is necessary toindicate a case that there is no single frequency position of an RMSIexisting SSB within a range that can be currently indicated. Moreover,if it is intended to inform a UE that a frequency position of an RMSIexisting SSB is located within a frequency range greater than afrequency range corresponding to the indication range, additionalsignaling for indicating such information is required. And, it is ableto inform the UE of a frequency position of an RMSI existing SSB locatedwithin a frequency range greater than a frequency range corresponding tothe indication range using spare states among the states that can beindicated using bits for PRB grid offset included in a PBCH content,i.e., a PBCH MIB.

For example, since 24 PRB grid offsets are indicated using 5 bits on aband FR1, maximum 8 states can be additionally defined. Since 12 PRBgrid offsets are indicated using 4 bits on a band FR2, maximum 4 statescan be additionally defined. If an indication range is configured in asingle direction, the additionally defined state(s) can be representedas follows. In the following, K indicates a value corresponding to afrequency range greater than a frequency range corresponding to theindication range.

-   -   First state: RMSI does not exist at a corresponding sync raster.    -   Second state: RMSI does not exist at a corresponding sync        raster, and K is 0.    -   Third state: RMSI does not exist at a corresponding sync raster,        and K is 255.    -   Fourth state: RMSI does not exist at a corresponding sync        raster, and K is 510.

Namely, in case of using the above-described method, if a currentlocation of a UE and a value for an indication range indicated with 8bits are set to O and N (0˜255), respectively, an indicated frequencyposition

can be expressed asIndicated position=O+N+K.

Here, if the first state is delivered to a UE, the UE may recognize thatthere is no RMSI existing frequency position within the indication rangeand detect SSB by moving to a frequency position indicated through an8-bit indicator and then performing a frequency scan again. The UEchecks a presence or non-presence of RMSI through PBCH included in theSSB. In case of the non-presence of the RMSI, the UE may repeat aprocess for obtaining information on an RMSI existing frequencyposition.

Besides, if an indication range is configured in both directions, theadditionally defined state(s) can be represented as follows.

-   -   First state: RMSI does not exist in a corresponding indication        range.    -   Second state: RMSI does not exist in a corresponding indication        range, and K is    -   Third state: RMSI does not exist in a corresponding indication        range, and K is −127 or 127, where a sign of K is equal to that        of N.    -   Fourth state: RMSI does not exist in a corresponding indication        range, and K is −254 or 254, where a sign of K is equal to that        of N.

If a current location of a UE and a value indicated with 8 bits are setto O and N (−127˜127), respectively, an indicated frequency position

can be expressed asIndicated position=O+N+K.

Here, if the first state is delivered to a UE, the UE may recognize thatthere is no RMSI existing frequency position within the indication rangeand obtain information on an RMSI existing frequency position throughadditional signaling for the first to fourth states by moving to afrequency position indicated through an 8-bit indicator and thenperforming a frequency scan again.

(5) Embodiment 5

Sync rasters currently defined in RAN4 are defined as Table 2 in thefollowing.

TABLE 2 NR Operating SS Block SS Block Range of GSCN Band SCS pattern¹(First-<Step size>-Last) n1 15 kHz Case A 7039-<1>-7224 n2 15 kHz Case A6439-<1>-6624 n3 15 kHz Case A 6022-<1>-6258 n5 15 kHz Case A2902-<1>-2973 30 kHz Case B 2911-<1>-2964 n7 15 kHz Case A[8740-<1>-8958] n8 15 kHz Case A 3091-<1>-3192 n20 15 kHz Case A2644-<1>-2727 n28 15 kHz Case A 2533-<1>-2667 n38 15 kHz Case A[8572-<1>-8958] n41 15 kHz Case A [9069]-<TBD>-[9199] 30 kHz Case C9070-<1>-9198 n50 15 kHz Case A 4780-<1>-5049 n51 15 kHz Case A4762-<1>-4764 n66 15 kHz Case A  7039-<1>-[7326] 30 kHz Case B 7048-<1>-[7317] n70 15 kHz Case A  6655-<1>-[6726] n71 15 kHz Case A2062-<1>-2166 n74 15 kHz Case A 4924-<1>-5052 n75 15 kHz Case A[4780-<1>-5049] n76 15 kHz Case A [4762-<1>-4764] n77 30 kHz Case C 9628-<1>-10247 n78 30 kHz Case C 9628-<1>-9969 n79 30 kHz Case C[10393]-<TBD>-[10802] NOTE 1: SS Block pattern is defined in section 4.1in [TS 38.213].

In Embodiment 5, it is able to indicate a frequency position of an RMSIexisting SSB with reference to Global Synchronization Channel Number(GSCN) shown in Table 2. Here, assuming that an 8-bit indicator is usedto indicate a frequency position of an RMSI existing SSB, the whole GSCNis divided into 256 (8-bit) units and the frequency position of the RMSIexisting SSB can be indicated within the 256 ranges.

For example, assuming that 256 units are regarded as a single cluster,as a UE is aware of a GSCN number accessed by the UE, the UE candetermine a remainder found by dividing the GSCN number by 256 as itsown reference position within the cluster. And, the UE can discover afrequency position of an RMSI existing SSB by moving within the clusterby an indicated position from the determined reference position.

Meanwhile, for an efficient operation of a UE, it is necessary toindicate a case that there is no single frequency position of an RMSIexisting SSB within a current cluster. To this end, it is able to informthe UE of a frequency position of an RMSI existing SSB located within afrequency range greater than a frequency range corresponding to theindication range using spare states among the states that can beindicated using bits for PRB grid offset included in a PBCH content,i.e., a PBCH MIB.

For example, since 24 PRB grid offsets are indicated using 5 bits on aband FR1, maximum 8 states can be additionally defined. Since 12 PRBgrid offsets are indicated using 4 bits on a band FR2, maximum 4 statescan be additionally defined. And, the additionally defined state(s) canbe represented as follows.

-   -   First state: RMSI does not exist within a corresponding sync        raster. Move to a frequency position indicated within a        corresponding cluster.    -   Second state: RMSI does not exist within a corresponding sync        raster. Move to a next cluster having a higher frequency.    -   Third state: RMSI does not exist within a corresponding sync        raster. Move to a next cluster having a lower frequency.

As a UE receives an indication of a first state, if a frequency positionof an RMSI existing SSB exists within a current cluster, the UE maydiscover an SSB by moving to an indicated position. In case of beingaware that an RMSI existing frequency position does not exist in thecurrent cluster like the second or third state, the UE performs afrequency scan again by moving to another cluster at a higher frequencyor another cluster at a lower frequency. Such indication helps the UE toreduce performing an unnecessary frequency scan.

Moreover, when a specific frequency position is indicated within acluster, if an RMSI existing SSB does not exist at the correspondingfrequency position, the UE determines that there is no frequencyposition of the RMSI existing SSB that can be currently indicated and isthen able to perform a frequency scan again by starting with theindicated frequency position. Such a method can prevent the UE fromperforming an unnecessary scan. In case of this method, since the secondstate and the third state are not used, the corresponding state can beused for the extension of the indication range.

(6) Embodiment 6

In Embodiment 6, it is able to indicate a frequency position of an RMSIexisting SSB with reference to Global Synchronization Channel Number(GSCN) shown in Table 2. Here, assuming that an 8-bit indicator is usedto indicate a frequency position of an RMSI existing SSB, the whole GSCNis divided into 256 (8-bit) units and the frequency position of the RMSIexisting SSB can be indicated within the 256 ranges.

For example, assuming that 256 units are regarded as a single cluster,as a UE is aware of a GSCN number accessed by the UE, the UE candetermine a remainder found by dividing the GSCN number by 256 as itsown reference position within the cluster. And, the UE can discover afrequency position of an RMSI existing SSB by moving within the clusterby an indicated position from the determined reference position.

Yet, in case of using an 8-bit indicator, a frequency position of an SSBcan be indicated within a single cluster range only. Therefore, if it isintended to inform a UE of a frequency position of an RMSI existing SSBwithin a frequency range greater than a single cluster, additionalsignaling for indicating such information is required. And, it is ableto inform the UE of a frequency position of an RMSI existing SSB locatedwithin a frequency range greater than a frequency range corresponding tothe cluster using spare states among the states that can be indicatedusing bits for PRB grid offset included in a PBCH content, i.e., a PBCHMIB.

For example, since 24 PRB grid offsets are indicated using 5 bits on aband FR1, maximum 8 states can be additionally defined. Since 12 PRBgrid offsets are indicated using 4 bits on a band FR2, maximum 4 statescan be additionally defined. And, the additionally defined state(s) canbe represented as follows.

-   -   First state: RMSI does not exist within a corresponding sync        raster. An indication range of ‘N’ is 0˜255.    -   Second state: RMSI does not exist within a corresponding sync        raster. An indication range of ‘N’ is 256˜511.    -   Third state: RMSI does not exist within a corresponding sync        raster. An indication range of ‘N’ is −256˜255.    -   Fourth state: RMSI does not exist within a corresponding sync        raster. An indication range of ‘N’ is −512˜257.

If a frequency position of an RMSI existing SSB exists within anindicated indication range, a UE may discover an SSB by moving to anindicated position. Although a frequency position within an indicationrange is indicated, if the RMSI existing SSB does not exist at theindicated frequency position, the UE determines that the frequencyposition of the RMSI existing SSB does not exist within the currentindication range and then discovers a frequency position of an RMSIexisting SSB by performing a frequency scan again by starting with theindicated frequency position. Such a method can prevent the UE fromperforming an unnecessary frequency scan.

Moreover, the UE may perform a frequency scan by directly moving to alowest or highest frequency in a manner of adding ‘RMSI does not existwithin a corresponding indication range’ to a state. The correspondingstate may be represented through a PRB grid offset or an additional8-bit indicator. Here, if the state is represented through an 8-bitindicator, a size of a cluster becomes smaller than 256. For example, ifthe above state exists as one of two types, a size of a cluster maybecome 254.

-   -   First state: RMSI does not exist within a corresponding        indication range. Move to a highest frequency position within        the corresponding indication range.    -   Second state: RMSI does not exist within a corresponding sync        raster. Move to a lowest frequency position within the        corresponding indication range.

(7) Embodiment 7

In Embodiment 7, it is able to indicate a frequency position of an RMSIexisting SSB with reference to Global Synchronization Channel Number(GSCN) shown in Table 2. Here, assuming that an 8-bit indicator is usedto indicate a frequency position of an RMSI existing SSB, the whole GSCNis divided into 256 (8-bit) units and the frequency position of the RMSIexisting SSB can be indicated within the 256 ranges.

For example, assuming that 256 units are regarded as a single cluster,as a UE is aware of a GSCN number accessed by the UE, the UE candetermine a remainder found by dividing the GSCN number by 256 as itsown reference position within the cluster. And, the UE can discover afrequency position of an RMSI existing SSB by moving within the clusterby an indicated position from the determined reference position.

Yet, in case of using an 8-bit indicator, a frequency position of an SSBcan be indicated within a single cluster range only. Therefore, if it isintended to inform a UE of a frequency position of an RMSI existing SSBwithin a frequency range greater than a single cluster, additionalsignaling for indicating such information is required. And, it is ableto inform the UE of a frequency position of an RMSI existing SSB locatedwithin a frequency range greater than a frequency range corresponding tothe cluster using spare states among the states that can be indicatedusing bits for PRB grid offset included in a PBCH content, i.e., a PBCHMIB.

For example, since 24 PRB grid offsets are indicated using 5 bits on aband FR1, maximum 8 states can be additionally defined. Since 12 PRBgrid offsets are indicated using 4 bits on a band FR2, maximum 4 statescan be additionally defined.

TABLE 3 NR Operating Downlink (DL) operating band Band BS transmit UEreceive n7 2620 MHz-2690 MHz n38 2570 MHz-2620 MHz n41 2496 MHz-2690 MHz

Moreover, as the bands n42, n7 and n38 in Table 3 share the samefrequency band but have different sync raster sizes 1.44 MHz, 900 kHzand 900 kHz, respectively, they have different GSCN numbers on the samefrequency band like Table 2. Hence, although a frequency position of anRMSI existing SSB is indicated, it is unclear that an indicated bandindicates which band exactly in aspect of UE. This is because a bandassumed by the UE as located thereon may be different from an actuallySSB detected band. Hence, to remove such ambiguity, it is necessary tosignal whether a size of a sync raster is 900 kHz or 1.44 MHz.

Meanwhile, since the problem about the ambiguity may be caused on a bandFR1, it is able to utilize 8 spare states that can be additionallydefined on the band FR1.

Namely, in order to indicate a frequency position of an RMSI existingSSB, maximum 8 states additionally defined on FR1 can be defined asTable 4, and maximum 4 states additionally defined on FR2 can be definedas Table 5.

TABLE 4 Offset from reference Raster ā_(Ā+5) SSB_subcarrier_offsetRMSI_PDCCH_config GSCN size 0 12 0~255  0~255 900 kHz 0 13 0~255 256~511900 kHz 0 14 0~255 −256~−1  900 kHz 1 12 0~255  0~255 1.44 MHz 1 130~255 256~511 1.44 MHz 1 14 0~255 −256~−1  1.44 MHz

TABLE 5 Offset from SSB_subcarrier_offset RMSI_PDCCH_config referenceGSCN 12 0~255  0~255 13 0~255 256~511 14 0~255 −256~−1 

If a frequency position of an RMSI existing SSB exists within anindicated indication range, a UE may discover an SSB by moving to anindicated position. Although a frequency position within an indicationrange is indicated, if the RMSI existing SSB does not exist at theindicated frequency position, the UE determines that the frequencyposition of the RMSI existing SSB does not exist within the currentindication range and then discovers a frequency position of an RMSIexisting SSB by performing a frequency again by starting with theindicated frequency position. Such a method can prevent the UE fromperforming an unnecessary frequency scan.

Besides, using 8 bits of a parameter (RMSI_PDCCH_config) for indicatinga PRB grid offset, it is able to indicate an RMSI non-existing range toa UE by adding ‘RMSI does not exist within a corresponding indicationrange’ as follows.

-   -   Fifteenth state of PRB grid offset: RMSI does not exist within a        corresponding indication range. The indication range is        indicated through 8 bits of RMSI_PDCCH_config.

(8) Embodiment 8

A position currently accessed by a UE is set as a reference frequencyposition, and it is able to signal a frequency position of an RMSIexisting SSB from the reference frequency position as a relative value.If 8 bits are used, it is possible to indicate total 256 relative SSBfrequency positions. In this case, an indication range can be configuredin a low or high frequency position direction from a current frequencyposition (i.e., a reference frequency position) [e.g., N=−127˜+128] orin a single direction [e.g., N=0˜255]. If an indication range isconfigured in a single direction, all UEs have the same frequency scandirection in case of an initial access, which can be defined in thestandard document.

Moreover, if it is intended to inform a UE of a frequency position of anRMSI existing SSB within a frequency range greater than a frequencyrange that can be indicated using an 8-bit indicator, additionalsignaling for indicating such information is required. And, it is ableto inform the UE of a frequency position of an RMSI existing SSB locatedwithin a frequency range greater than a frequency range corresponding tothe cluster using spare states among the states that can be indicatedusing bits for PRB grid offset included in a PBCH content, i.e., a PBCHMIB.

For example, since 24 PRB grid offsets are indicated using 5 bits on aband FR1, maximum 8 states can be additionally defined. Since 12 PRBgrid offsets are indicated using 4 bits on a band FR2, maximum 4 statescan be additionally defined.

Moreover, as the bands n42, n7 and n38 in Table 3 share the samefrequency band but have different sync raster sizes 1.44 MHz, 900 kHzand 900 kHz, respectively, they have different GSCN numbers on the samefrequency band like Table 2. Hence, although a frequency position of anRMSI existing SSB is indicated, it is unclear that an indicated bandindicates which band exactly in aspect of UE. This is because a bandassumed by the UE as located there on may be different from an actuallySSB detected band. Hence, to remove such ambiguity, it is necessary tosignal whether a size of a sync raster is 900 kHz or 1.44 MHz.

Meanwhile, since the problem about the ambiguity may be caused on a bandFR1, it is able to utilize 8 spare states that can be additionallydefined on the band FR1.

Therefore, in Embodiment 8 like Embodiment 7, in order to indicate afrequency position of an RMSI existing SSB, maximum 8 statesadditionally defined on FR1 can be defined as Table 4, and maximum 4states additionally defined on FR2 can be defined as Table 5.

If a frequency position of an RMSI existing SSB exists within anindicated indication range, a UE may discover an SSB by moving to anindicated position. Although a frequency position within an indicationrange is indicated, if the RMSI existing SSB does not exist at theindicated frequency position, the UE determines that the frequencyposition of the RMSI existing SSB does not exist within the currentindication range and then discovers a frequency position of an RMSIexisting SSB by performing a frequency again by starting with theindicated frequency position. Such a method can prevent the UE fromperforming an unnecessary frequency scan.

Besides, using 8 bits of a parameter (RMSI_PDCCH_config) for indicatinga PRB grid offset, it is able to indicate an RMSI non-existing range toa UE by adding ‘RMSI does not exist within a corresponding indicationrange’ as follows.

-   -   Fifteenth state of PRB grid offset: RMSI does not exist within a        corresponding indication range. The indication range is        indicated through 8 bits of RMSI_PDCCH_config.

In the above-described Embodiments 1 to 8, among the states that can beindicated, ‘RMSI does not exist within a corresponding band’ or ‘RMSIdoes not exist within a corresponding cluster’ corresponding to aspecific state is a state available in case that a specific serviceprovider entirely operates a single band or cluster. If a serviceprovider operates a prescribed portion of an NR band, since it is unableto know information on all frequency positions of SSB within thecorresponding band, it is unable to indicate a state ‘RMSI does notexist within a corresponding band’ to a UE.

Therefore, as various service providers divide a specific band, when aportion of the specific band is operated by being assigned to eachservice provider, if RMSI does not exist on the partial band operated bya specific service provider, it may be able to instruct the UE to scanpositions other than a frequency position of an SSB on the band operatedby the specific service provider.

Namely, it is not mandatory for RMSI to exist at a frequency position ofSSB indicated to the UE. If RMSI does not exist within a band portionoperated by a service provider, the corresponding service provider mayindicate a frequency position of SSB existing in a band portion operatedby another service provided within the same NR band and enable afrequency position of an RMSI existing SSB to be discovered through afrequency scan from the corresponding frequency position.

<3. RMSI COREST Configuration of Minimum Bandwidth 10 MHz>

In an NR system, it is necessary to define a new configuration table fora minimum channel bandwidth of 10 MHz for an SSB having a subcarrierspacing of 15 kHz. Particularly, in case of a band n41 of Table 2, as aminimum channel bandwidth of 10 MHz used by an SSB having a subcarrierspacing of 15 kHz is used, it is necessary to consider a configurationfor RMSI CORESET supportive of the band n41.

In order to reduce the number of SSBs for a wide minimum channelbandwidth such as 10 MHz, 40 MHz and the like, it is necessary to narrowdown targets of all SSB candidates [down selection]. In case of a 15 kHzsubcarrier spacing of a band n41, as a down selection value is 3, a syncraster value increases to 4.32 MHz. Hence, in case of supporting a syncraster of a big value for the subcarrier spacing of 15 kHz, an NR shouldconsider a new configuration table for a 15 kHZ subcarrier spacing of anSSB having a minimum channel bandwidth of 10 MHz. Moreover, in making aCORESET configuration table, network operation flexibility should beconsidered according to a state of a network bandwidth. Hence, RMSICORESET configuration for a 15 kHz subcarrier spacing and a minimumchannel bandwidth of 10 MHz should be designed to support 10 MHz BW˜20MHz BW.

Meanwhile, although 4 bits for configuring RMSI CORESET are designatedwithin MIB, the 4 bits are not enough to represent all candidates of anRB offset indicating a position of RMSI CORESET with reference to SSB.To solve such a problem, it is able to consider a method of defining twoconfiguration tables according to an RMSI CORESET bandwidth andselecting a single table from RAN4. Yet, in case of the above-describedmethod, there is a problem that a channel bandwidth and a bandwidth ofRMSI CORESET can be limited. Hence, the above-described message my notbe appropriate for network resource utilization.

Therefore, it is proposed to add an indication bit for a dynamicselection between two configuration tables to an MIB. To this end, it isable to utilize 1 bit among bits reserved for SSB index indicationlocated within a PBCH content, i.e., the MIB. Namely, with total 5 bitsresulting from adding 1 bit of a new MIB to 4 bits defined in advance,it is able to design a new configuration table for COREST configuration.Namely, for the CORESET configuration, an additional 1 bit is needed aswell as 4 bits defined in advance. Such an additional 1 bit can utilize1 bit among bits reserved for SSB index indication.

Referring to FIG. 10, a communication apparatus 1100 includes aprocessor 1110, a memory 1120, an RF module 1130, a display module 1140,and a User Interface (UI) module 1150.

The communication device 1100 is shown as having the configurationillustrated in FIG. 11, for the convenience of description. Some modulesmay be added to or omitted from the communication apparatus 1100. Inaddition, a module of the communication apparatus 1100 may be dividedinto more modules. The processor 1110 is configured to performoperations according to the embodiments of the present disclosuredescribed before with reference to the drawings. Specifically, fordetailed operations of the processor 1110, the descriptions of FIGS. 1to 9 may be referred to.

The memory 1120 is connected to the processor 1110 and stores anOperating System (OS), applications, program codes, data, etc. The RFmodule 1130, which is connected to the processor 1110, upconverts abaseband signal to an RF signal or downconverts an RF signal to abaseband signal. For this purpose, the RF module 1130 performsdigital-to-analog conversion, amplification, filtering, and frequencyupconversion or performs these processes reversely. The display module1140 is connected to the processor 1110 and displays various types ofinformation. The display module 1140 may be configured as, not limitedto, a known component such as a Liquid Crystal Display (LCD), a LightEmitting Diode (LED) display, and an Organic Light Emitting Diode (OLED)display. The UI module 6050 is connected to the processor 1110 and maybe configured with a combination of known user interfaces such as akeypad, a touch screen, etc.

The embodiments of the present invention described above arecombinations of elements and features of the present invention. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent invention may be constructed by combining parts of the elementsand/or features. Operation orders described in embodiments of thepresent invention may be rearranged. Some constructions of any oneembodiment may be included in another embodiment and may be replacedwith corresponding constructions of another embodiment. It is obvious tothose skilled in the art that claims that are not explicitly cited ineach other in the appended claims may be presented in combination as anembodiment of the present invention or included as a new claim by asubsequent amendment after the application is filed.

A specific operation described as performed by a BS may be performed byan upper node of the BS. Namely, it is apparent that, in a networkcomprised of a plurality of network nodes including a BS, variousoperations performed for communication with a UE may be performed by theBS, or network nodes other than the BS. The term ‘BS’ may be replacedwith the term ‘fixed station’, ‘Node B’, ‘evolved Node B (eNode B oreNB)’, ‘Access Point (AP)’, etc.

The embodiments of the present invention may be achieved by variousmeans, for example, hardware, firmware, software, or a combinationthereof. In a hardware configuration, the methods according to exemplaryembodiments of the present invention may be achieved by one or moreApplication Specific Integrated Circuits (ASICs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

In a firmware or software configuration, an embodiment of the presentinvention may be implemented in the form of a module, a procedure, afunction, etc. Software code may be stored in a memory unit and executedby a processor. The memory unit is located at the interior or exteriorof the processor and may transmit and receive data to and from theprocessor via various known means.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent disclosure. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of thedisclosure should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein.

INDUSTRIAL APPLICABILITY

Although the above-described method of receiving system information andapparatus therefor are described by focusing on an example of beingapplied to the 5G NewRAT system, they are applicable to various kinds ofmobile communication systems as well as to the 5G NewRAT system.

What is claimed is:
 1. A method for receiving remaining minimum systeminformation (RMSI) by a user equipment (UE) in a wireless communicationsystem, the method comprising: detecting, at a specific frequencyposition for a first synchronization raster, a first synchronizationsignal block (SSB) including a Synchronization Signal (SS) and aPhysical Broadcasting Channel (PBCH); and receiving the RMSI based oninformation related to RMSI scheduling included in the PBCH, wherein,based on RMSI related to the first SSB not being present, the RMSI isreceived based on a relative position between the first synchronizationraster and a second synchronization raster, wherein the relativeposition is related to a second SSB having the RMSI, and wherein therelative position is obtained based on the information related to theRMSI scheduling.
 2. The method of claim 1, wherein a frequency range inwhich the RMSI is not present is obtained based on a value included inthe information related to the RMSI scheduling, and wherein thefrequency range in which the RMSI is not present includes the firstsynchronization raster.
 3. The method of claim 2, wherein a position ofthe second synchronization raster is not obtained in a state in whichthe frequency range is obtained based on the value included in theinformation related to the RMSI scheduling.
 4. The method of claim 1,wherein a third SSB not having the RMSI is received at a frequencyposition not included in the first synchronization raster and the secondsynchronization raster.
 5. A device configured to receive remainingminimum system information (RMSI) in a wireless communication system,the device comprising: a memory; and a processor connected with thememory, wherein the processor is configured to control to: detect, at aspecific frequency position for a first synchronization raster, a firstsynchronization signal block (SSB) including a Synchronization Signal(SS) and a Physical Broadcasting Channel (PBCH), and receive the RMSIbased on information related to RMSI scheduling included in the PBCH,wherein, based on RMSI related to the first SSB not being present, theRMSI is received based on a relative position between the firstsynchronization raster and a second synchronization raster, wherein therelative position is related to a second SSB having the RMSI, andwherein the relative position is obtained based on the informationrelated to the RMSI scheduling.
 6. The device of claim 5, wherein afrequency range in which the RMSI is not present is obtained based on avalue included in the information related to the RMSI scheduling, andwherein the frequency range in which the RMSI is not present includesthe first synchronization raster.
 7. The device of claim 6, wherein aposition of the second synchronization raster is not obtained in a statein which the frequency range is obtained based on the value included inthe information related to the RMSI scheduling.
 8. The device of claim5, wherein a third SSB not having the RMSI is received at a frequencyposition not included in the first synchronization raster and the secondsynchronization raster.
 9. The method of claim 1, further comprising:based on the RMSI related to the first SSB not being present,determining a frequency position of the second SSB based on the relativeposition, wherein the relative position indicates the frequency positionof the second SSB relative to the specific frequency position of thefirst SSB.
 10. The device of claim 5, wherein the processor is furtherconfigured to control to: based on the RMSI related to the first SSB notbeing present, determine a frequency position of the second SSB based onthe relative position, wherein the relative position indicates thefrequency position of the second SSB relative to the specific frequencyposition of the first SSB.